title: Distribution of amoxicillin-resistant oral streptococci in dental plaque specimens obtained from Japanese children and adolescents at risk for infective endocarditis.
abstract: BACKGROUND
  Infective endocarditis (IE) is known to be a life-threatening disease and prevention of its onset is important. Oral amoxicillin (AMPC) is generally prescribed to patients at risk for IE prior to undergoing risky procedures, such as invasive dental treatments. We previously found that approximately 5% of systemically healthy Japanese subjects harbor strains highly resistant to AMPC. In the present study, the prevalence of strains in patients at risk for IE was investigated.
  
  
  RESULTS
  Thirty-four Japanese children and adolescents designated at risk for IE by their cardiovascular surgeons participated. Dental plaque specimens were obtained at recall examinations for dental checkups and placed in sterile phosphate-buffered saline, then diluted and streaked onto selective media for oral streptococci and also media containing AMPC. Nine strains with a minimum inhibitory concentration of AMPC of 16μg/mL or more were isolated from 7 of the subjects (20.6%), each of which was also resistant to other antibiotics analyzed except for new quinolone drugs. The 16S rRNA sequence of each strain demonstrated that all were oral streptococcal species. In addition, dental plaque specimens collected from 5 subjects after an additional interval of 3-4 months showed that 2 harbored the same clones at different time points.
  
  
  CONCLUSIONS
  These findings suggest a higher prevalence of AMPC-resistant strains in children and adolescents at risk for IE as compared to systemically healthy subjects. Thus, alternative antibiotics should be considered for such subjects when performing prophylaxis procedures.
authors.affiliation: Department of Pediatric Dentistry, Division of Oral Infection and Disease Control, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Nemoto
authors.forename: Ryota
authors.initials: R
authors.lastname: Nomura
authors.forename: Takashi
authors.initials: T
authors.lastname: Ooshima
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Nakano
mesh_terms: D000293:Adolescent; D000658:Amoxicillin / Q000494:pharmacology*; D000668:Ampicillin Resistance; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D019072:Antibiotic Prophylaxis; D044466:Asian People; D002648:Child; D002675:Child, Preschool; D003773:Dental Plaque / Q000382:microbiology*; D004696:Endocarditis / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D012306:Risk; D013291:Streptococcus / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D000900:Anti-Bacterial Agents; D000658:Amoxicillin
keywords: Endocarditis; Infectious disease; Patient care; Prevention; Risk factors